Machines having extensible arms with suction cups for lifting and holding non-porous articles generally include valve mechanisms for venting the suction cups and releasing the articles hold thereby at desired times or positions. Prior art machines of this type have utilized various mechanical systems for actuating the valve mechanisms. These mechanical systems typically comprise a number of moving parts for opening and closing the vent valve at the desired times and/or positions. Because of the high cycling rates of the contacting mechanical parts, they frequently wear out or break, leading to relatively high maintenance costs.